If you have an itchy rash that resembles a Christmas tree, you may have a common skin condition called pityriasis rosea

• Pityriasis rosea is a common skin condition that causes a set of temporary red, scaly rashes.
• These mild rashes aren't contagious and usually clear up without medical treatment in 10 weeks or less.

Pityriasis rosea — which means "fine pink scale" — is a mild skin condition that typically appears as small patches of inflamed and scaly skin. These patches most often appear on your chest, abdomen, or back.

This fairly common skin condition can affect anyone, though women and people between the ages of 10 and 35 are more likely to develop it, says Dr. Cory Gaskins, a certified dermatologist and resident medical expert at BestBotox.ca.

This rash might alarm you, if you notice it on yourself or a family member — but here's some good news: It's not contagious and often doesn't require medical treatment.

Read on to learn how to recognize pityriasis rosea and how to treat your symptoms.

Note: Pityriasis rosea is commonly called "Christmas tree rash" because of its characteristic tree-like pattern: one large oval patch that branches out into smaller pink or dark patches.

Signs and symptoms

Pityriasis rosea doesn't just involve a rash.

Before you notice any skin changes, you might also experience some flu-like symptoms, according to Dr. Jaspreet Oberoi, a board-certified pathologist and founder of LifePathDoc. These symptoms might include fever, headaches, sore throat, and a stuffy nose.

After the flu symptoms resolve — usually within a week or two — a skin lesion of about 4 inches in size will appear. This first lesion is called the herald patch, Oberoi says. The herald patch appears in up to 90% of pityriasis rosea cases and typically has a round or oval shape.

Here's how the rash will progress, according to Oberoi and Gaskins:

• Within 2 weeks after the herald patch arrives, smaller spots or bumps will emerge and spread across your face, chest, back, and abdomen in a pattern that resembles the branches of a pine or Christmas tree.
• These smaller spots usually have a pinkish or salmon color in people with light skin. In people with darker skin, the spots typically range from dusky violet to deep brown in color.
• You may experience itching that ranges from mild to severe. About 25% of people experience severe itching.
• The rash may also cause post-inflammatory hypo- or hyperpigmentation, or spots that have a lighter or darker appearance than your typical skin tone. These spots more often affect people with darker skin and may take 6-12 months to clear up.

Causes

Experts don't know the exact cause of pityriasis rosea, though many believe it relates to a viral infection, Gaskins says.

That's because pityriasis rosea initially presents with generic flu-like symptoms before the actual rash appears, like many other viral infections. Another rash that follows this pattern is rubella, which is caused by a virus. Pityriasis rosea has also been linked to herpes virus 6 and 7, according to Oberoi.

What's more, some people have also developed rashes that resemble pityriasis rosea:

• After receiving bacterial vaccines such as Bacillus Calmette-Guerin (BCG) and Pneumococcus.
• When taking certain medications, including captopril, D-penicillamine, clonidine, and barbiturates.

How to get a diagnosis

Pityriasis rosea can be diagnosed by its characteristic appearance and the distribution of its lesions, Gaskins says. Since the rash is so distinct, a dermatologist or other healthcare professional can usually diagnose it by sight alone.

That said, make sure to provide as much information as you can about your symptoms and when they first appeared.

You'll also want to let your care team know if you experienced any aches, pains, or other flu-like symptoms before the rash first appeared.

If your doctor has any doubts about the cause of the rash, they may recommend a biopsy, skin scraping, or blood tests to confirm the diagnosis and rule out other conditions.

Important: Make sure to let your care team know if you could be pregnant or have recently had an organ transplant. They may want to monitor your symptoms more closely.

How to treat pityriasis rosea

Pityriasis rosea clears up on its own, usually within about 10 weeks.

There's no specific treatment that will help the rash go away sooner. Instead, treatment typically focuses on improving your symptoms, like itching and lingering spots.

Specifically, your care team may recommend:

• Hydrocortisone or other steroid creams to ease itching and inflammation.
• Antihistamines to help relieve any lingering flu symptoms.
• UVB phototherapy to help reduce skin inflammation.
• Cool or lukewarm baths with colloidal oats to minimize itching.

Your doctor or dermatologist can offer more guidance on treatments for your specific symptoms.

Important: You'll want to avoid using products intended to treat candida (yeast) and other fungal infections, as they can worsen your rash.

Self-care strategies

These strategies can help reduce discomfort while you wait for the rash to clear up:

• Wear loose-fitting clothes and avoid exposure to hot environments, such as direct sunlight and hot tubs, to keep your rash from becoming itchier.
• Avoid intense exercise and other activities that can heat up your body, as this can worsen your rash.
• Avoid antibacterial soaps or harsh cleansers. Instead, opt for gentle bath products and moisturizers without fragrance to avoid worsening your rash and itching.
• Apply broad spectrum sunscreen with a minimum of SPF 30 to all exposed parts of your skin. It's best to wear sunscreen every day, but it becomes especially important if you have pityriasis rosea since sunburn can worsen the rash.

If the rash lasts for more than three months, you'll want to make an appointment with a doctor or dermatologist, Gaskins says. They can help rule out other conditions that may be causing the rash.

Insider's takeaway

Pityriasis rosea is a relatively mild skin rash with a distinct, tree-like appearance. The rash typically clears up on its own within 3 months. It's not contagious, and you won't necessarily need medical attention — plus, once it clears up, you most likely won't experience it again.

That said, this rash may cause moderate to severe itching, and it can also cause lingering skin discoloration. If you're dealing with any uncomfortable or persistent symptoms, a doctor or dermatologist can recommend helpful treatments.